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Neuroplasticity, Brain Fitness and Cognitive Health News


How the Brain of a Blind Person Rewires Itself

Do blind peo­ple real­ly have a sharp­ened sense of hear­ing? What is the expla­na­tion? This arti­cle reports the work of Ger­man researchers who looked at blind peo­ple’s brains to try to answer these ques­tions. They found out that indeed, blind peo­ple can under­stand speech even if sped up beyond the max­i­mum rate that sight­ed peo­ple can under­stand. This seemed pos­si­ble because the brain areas devot­ed to vision in peo­ple with eye sight turned out to be respond­ing to speech in blind peo­ple.

10 syl­la­bles per sec­ond [is] the absolute lim­it of com­pre­hen­sion for sight­ed peo­ple. Blind peo­ple, how­ev­er, can com­pre­hend speech sped up to 25 syl­la­bles per sec­ond.

brain scan­ner revealed that in blind peo­ple the part of the cere­bral cor­tex that nor­mal­ly responds to vision was respond­ing to speech.…somehow an unsight­ed per­son­’s brain rewires itself to con­nect audi­to­ry regions of the brain to the visu­al cor­tex.

A per­fect exam­ple of neu­ro­plas­tic­i­ty! Do you think this hap­pens  1) only in peo­ple who are born blind, or  2) only in peo­ple who lose sight lat­er in life,  or 3)  in both cas­es?

The answer is 2). Indeed, to be rewired con­nec­tions need to pre­ex­ist. This is not the case in peo­ple who are born blind since their visu­al cor­tex has nev­er received any visu­al stim­u­la­tion. It is only in peo­ple who lose sight lat­er in life, that the visu­al con­nec­tions can be rerout­ed to process audi­to­ry infor­ma­tion.

How does it work?

The fact is that most of our sens­es have some inter­act­ing cir­cuit­ry between them, which is called cross modal­i­ty. […] These con­nec­tions between visu­al and audi­to­ry regions of the brain become strength­ened after los­ing sight.

Also, some regions of cere­bral cor­tex that bor­der visu­al and audi­to­ry cor­tices […] expand ter­ri­to­ry in blind peo­ple to make use of the idle cir­cuit­ry in visu­al cor­tex.

Relat­ed post: Brain Plas­tic­i­ty: How learn­ing changes your brain

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As seen in The New York Times, The Wall Street Journal, BBC News, CNN, Reuters,  SharpBrains is an independent market research firm tracking how brain science can improve our health and our lives.

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